Dear all, the time has come to do an attempt to make an open source charge only BMS which can interface over CAN bus with the VESC ( BMS interface of the VESC ), a Metr.at module and many other stuff who are already working with the DieBieMS (protocol will be very close, if not equal ).
For an extremely long time I have been procrastinating this project because I wanted to make a BMS that fit all the needs of every application from very small to very big LEV’s. However I always ran into cost and complexity which also resulted in a ver big sized BMS once more. I long aimed to add BLE, isolated current measurement and isolated CAN, main current switching like the DieBieMS but the most recent Esk8 trends remove the need of all of them. We no longer need BLE on a BMS since most of use already interface directly with the VESC trough BLE or trough an added dongle like the Metr.at. With the resent implementation of main current switching in the ESC’s directly we also no longer need that to be done by the BMS, although ideally the BMS would protect the battery against a load at all cost, we sort of already accepted in charge only builds that when configured correctly it is “ok” enough to have the ESC in control. This is only for the DIY marked, for consumer electronics this is of course not acceptable and does also not comply with UN test requirements. The recent implementation of listening to a BMS in the VESC firmware motivated me / made me accept that ChargeOnly can be acceptable for DIY.
Now that I have concluded that this is acceptable I am going to attempt to make an affordable charge only solution of which the hardware and firmware sources will be full open, just like the DieBieMS, I will also attempt to make it a size that is compelling to be easily implemented in compact builds. A very important thing which I would like to remain implemented on the BMS is a method to measure the battery current to be able to estimate the internal resistance, SoC, SoH and usage in general of the pack. So the main battery current will still run trough the BMS in the ground side. Charge current will be switched and controlled high side. I will also include a USB PD interface to allow for a future USB PD DCDC converter extension to use the Esk8 battery as a power bank.
Over the course of the upcoming months I will be share the progress here and will be curious on your feedback. I am open to mechanical size critics but also open for advice for aluminium CNC modification parties who could, if they want, can eventually develop a mounting / cooling solution.
My aim for the BMS is to work with chargers up to 30Amps (switch and control) and discharge currents up to 150A (only measure). The operational voltage will be from 6Series connected cells up to 16Series.